The invention relates to a high efficiency vertical tail assembly combined with a variable wing geometry for large pitch angles, mainly for all-wing aircraft, particularly for delta-type aircraft, wherein the vertical tail is tiltable about an axis in the wing plane, which axis extends in parallel to the longitudinal axis of the fuselage. Such a configuration is known from the German Patent Publication (DOS) No. 2,348,201. The vertical tail described and illustrated in said prior publication has a variable geometry, wherein rectangularly shaped vertical tail portions may be tilted or hinged about axes parallel to the longitudinal axis of the fuselage.
U.S. Pat. No. 3,104,079 discloses a space glider which is lifted off the ground by means of a rocket, preferably for carrying supplies to satellites. After completion of its mission the space glider returns to the base of departure. Such a flying body is constructed as an all-wing flying body, which comprises tail unit members located at the rear ends of the lifting surface on both sides of the fuselage. These tail unit members are tiltable about horizontal axes. The tail unit members are folded in or retracted during the so-called "piggy-back" flight; during self-sustained flight the tail unit members must be extended. The overhead tail unit members and the lateral vertical tail means, particularly at large angles of attack, are still situated substantially in the shadow of the wing, especially since an additional surface which lengthens the wing tip, is extended at the same time, whereby one half of the vertical tail unit or assembly surfaces becomes nearly ineffective. However, when such aircrafts are used as "gliders", these angle of attack problems occur only to a limited extent. The German Patent Publication (DAS) No. 1,056,482 describes a tail unit assembly wherein the flappable or hingeable wing surface portions are hingeable downwrdly into a vertical plane. Tilting of such vertical tail arrangements at the wing tips through an angle of about 45.degree. is also known already. However, such configurations also do not allow extremely large angles of attack within the so-called post-stall range.
Conventional vertical tail assemblies are usually rigidly attached to the back of the fuselage tail. However, such an arrangement results in severe disadvantages when flying with high angles of attack. For example, the vertical tail unit is shadowed by the fuselage and partially by the wing and the elevator assembly. As a result, such a vertical tail unit gets more and more into the wake field of the wing, fuselage, and elevator assembly whereby the local incident flow conditions of the vertical tail assembly become increasingly worse, for example, due to a lessened dynamic pressure, whereby the effectiveness is reduced and the effective side slip angle at the vertical tail unit becomes smaller than the geometric side slip angle. Furthermore, the effective sweep-back of the fin and of the vertical tail increases, and the profile of the vertical tail unit becomes increasingly disadvantageous because the profile structure extending perpendicularly to the leading edge gradually becomes a lateral edge.
The above shows that the contributions of an overhead vertical tail unit to the stability of the craft during side slip flight at high angles of attack become increasingly less effective. The effectiveness of the vertical tail is also simultaneously lost. Such loss may be avoided, when low positioned vertical tail units are used. Until recently, however, such low positioned vertical tail units could not be constructed with the desired dimensions, that is, they could not be constructed with a sufficient aspect ratio and area size.